Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - xci: Bump Bifrost components to the HEAD of Rocky release

    The bifrost and ironic SHAs are from the Stein release which is still
    in early days of development. We should use Rocky SHAs for the time
    being. However, bifrost from Rocky does not support Ansible > 2.4 so
    we have to use bifrost from master branch but all the ironic components
    have to be from the Rocky release.

    Change-Id: I1acb28e4a292c774d681519517be19a2da230851
    Signed-off-by: Markos Chandras <mchandras@suse.de>